Primary open-angle glaucoma (POAG) is a leading causes of blindness and identification of a gene for this condition would have profound implications. POAG results from impaired aqueous humor outflow in the eye. Trabecular meshwork proteoglycans are the most likely candidates for regulating the outflow resistance of the aqueous humor and, thus, are one of the determinants of intraocular pressure. Identification of these proteoglycans is important in understanding the nature and mechanism of the regulation of aqueous outflow. This proposal seeks to complete our identification and characterization of trabecular proteoglycans. This work will be facilitated by the availability of new proteoglycan sequences allowing production of specific core protein peptide antibodies and oligonucleotides. A trabecular meshwork cDNA expression library will be screened by peptide antibodies and/or by degenerate oligonucleotides made against the unique trabecular meshwork proteoglycan sequences identified by us. We will localize each of these proteoglycans in the trabecular meshwork using immunohistochemistry. These complementary approaches will allow the identification of the important trabecular meshwork proteoglycans. Based on several independent lines of evidence that suggest a fundamental role of proteoglycans in regulating the aqueous outflow through the trabecular meshwork, we propose that these proteoglycans are ideal candidate genes for glaucoma. POAG families with a clear pattern of autosomal dominant inheritance will be part of a study utilizing single stranded conformation analysis or denaturing gradient gels to determine if a specific proteoglycan may be the genetic defect in one or more of these families. It is our view that POAG is a heterogeneous group of disorders, so that each of these families may actually represent a defect in a different proteoglycan or extracellular matrix component. The ultimate goal of this grant proposal is to identify one or more POAG genes. This may, in turn, lead to earlier detection and new therapeutic approaches to this insidious cause of human blindness.